Method of graduating dials



(No Model.)-

B. L. .WEBB.

METHOD OF GRADUATING DIALS. No. 338,123. Patented Mar. 16, 1886.

I d zw N. PETERS. Piwluinnogmpher, Washingon, 04 C- NITED STATES PATENT OFFICE.

RODOLPHUS L. YVEBB, OF N FAV BRITAIN, CONNECTICUT.

METHOD OF GRADUATING DIALS.

QPECIPICATION forming part of Letters Patent No. 338,123, dated March 16, 1886.

Application filed July 13, 1885.

T0 on whom, it may concern.-

Be it known that I, RoDoLrHUs L. WEBB, of New Britain, in the county of Hartford and State of Connecticut, have invented a new Im provementin Graduating Dials; and Idohereby declare the following, when taken in connection with accompanying drawings and the letters of reference marked thereon, to be a full, clear, and exact description of the same, and which said drawings constitute part of this specification, and represent, in

Figure l, a face View of the graduated dial; Fig. 2, a perspective viewof the die, looking upon its face.

This invention relates to an improvement in graduating dialssuch as used for weighingscales, mathematical instruments, and other purposes, and such as are usually made from metal or other suitable material, and in which the graduating-lines are produced by cutting or impressing the surface.

In the more general practice in graduating this class of dials a circular or ring-shaped die is prepared having upon its surface ribs corresponding to each and every mark, radial and concentric, required. to be produced on the surface. Then the plate to be graduated is placed beneath the die and sufficient pressure brought to bear upon the die to impress the surface of the plate and give to it the graduating-lines.

The construction ofa die in full circle to thus produce the graduations at a single operation is not only expensive, but extremely difficult, owing to the fact that the face of the die must be out while the steel is in a soft condition, and then must be hardened and tempered. The operation of hardening and tempering is liable to, and generally does,warp or twist the die, so that its surface is not in the perfect plane it should be to give an equal impression at every point upon the plate, and various expedients are required to be resorted to to overcome this difficulty. So great is this difficulty that in the finer class of work the graduation is produced by cutting each individual line; but this is too expensive an operation for the more common class of dials-such as used for weighingscales, and in many of the cheaper mathematical instruments.

The object of my invention is to avoid the Serial No. 171,539. (No model.)

difficulties attending the construction and use of a ring-shaped die; and it consists in the employment of a segment-shaped die, in length a submultiple of the full circle to be graduated, and having upon its face ribs correspond ing to the lines of graduation for its submultiple part of the full circle, and so that by successive applications of the die to the plate the full and complete circle is graduated, as more fully hereinafter described.

In the illustration the graduations are rep resented as of a decimal character.

The die A, Fig. 2, is a segment of the circle to be graduated, the segment in length a submultiple of the full circle, and, as illustrated, is in length one-fifth of the full circle. Its face is provided with ribs corresponding to the graduations required for that one-fifth of the full circle. The die thus constructed is arranged in the press in the usual manner for arranging dies to impress the surface of metal. The plate, B, to be graduated is placed beneath the die, and should be held so that it may be rotated in a circle corresponding to the seg ment and the,circle to be gradnatedsay as upon a pin through the central hole, a, c0ncentric with the segment. The plate is first presented, say, for the first division, from b to d,- that portion in'ipressed, the plate is turned to bring the second division, (I to e, beneath the die; that portion impressed, then the plate again turned to bring the third division, from c tof, beneath the die; and that portion impressed, again turned to bring the portionf to g beneath the press; and that impressed, then again turned to bring the last division, from g to b, beneath the die, and that portion impressed and the circle completed. Each division is brought upon the same portion of the bed and beneath the die, so that a perfect uniformity of impression is necessarily produced, and the graduation will be of the most perfect character, not only in the divisions, but in depth of impression. By constructing the die to consist of a submultiple of the full circle the difficulties attending the hardening and tempering are avoided, as the short segment itself is not liable to twist or warp as is a continuous ring, and not only is the difficulty attending the of the full circle, and presenting the plate to he graduated to the said die by successive steps, each step corresponding to the length of the segment, whereby the predetermined number of steps indicated by the length of the segment will complete the graduation of the full circle substantially as described.

RODOLPHUS L. WEBB,

\Vitnesses:

JOHN E. EARLE, FRED. (J. EARLE. 

